The invention relates to a card reader with at least two transport rollers for the card arranged one after the other in the card infeed direction.
Card readers are used for data exchange, for example with a magnetic card, on the magnetic strip of which the data are stored, or with a chip card, on the chip or integrated circuit of which the data are stored.
Card readers with transport rollers are known, which draw the card into a position for data exchange and, after the data exchange, either transport it back again or transport it further in the infeed direction. In the data exchange position, the card is read by means of a reading head, which lies opposite a middle transport roller and thus simultaneously forms the opposing support for the transported card. Before and after this middle transport roller a further transport roller is provided in each case, all three of the transport rollers being deflectable out of the card path against the action of a restoring force.
In this known card reader, when the card, driven by the middle transport roller, is moved backwards and forwards past the write/read head for an exchange of data, the card is forced to run into the front or rear transport rollers, which have not been deflected, so that these are deflected if the occasion arises. This striking of the card against other transport rollers, especially while an exchange of data is currently taking place, has an adverse effect on the way in which the card reader works and can lead to faults and errors in the data exchange.
It is therefore the object of the invention to develop a card reader of the type mentioned in the introduction in such a way that, if possible, a card is not able to strike against other transport rollers while it is being transported by the one transport roller.
According to the invention, this object is achieved in that the transport rollers are provided on a pivot arm, which can be pivoted against the action of a restoring force in a plane at right angles to the card path, at a distance from the pivot axis of the pivot arm.
The important advantage of the card reader according to the invention consists in its transport rollers being pivoted further out of the card path the further they are spaced from its pivot axis when the pivot arm is displaced. Therefore, when a transport roller on the pivot arm is deflected by the card thickness of a card that has been fed in, all transport rollers lying further from the pivot axis are deflected, i.e. pivoted out of the card path, by more than the card thickness.
The pivot axis of the pivot arm can be provided after or before the transport rollers on the pivot arm in the card infeed direction.
With particular preference, a pivot arm, the pivot axis of which is provided after its transport rollers in the card infeed direction, and a pivot arm, the pivot axis of which is provided before its transport rollers in the card infeed direction, are coupled together so that their movements oppose one another. By means of this measure, it is ensured that both pivot arms always pivot together like a pair of scissors if the card, which is fed in, deflects one of the transport rollers out of its card path.
The opposing movement coupling can, for example, be achieved by the two pivot arms being connected together in an articulated manner between their two pivot axes. It is of particular advantage if the two pivot arms are connected together in an articulated manner via the axis of rotation of a transport roller common to both pivot arms. If this common transport roller for both pivot arms is also the nearest transport roller to the pivot axes, all other transport rollers are always deflected further than this common transport roller.
Advantageously, a read and/or write head of the card reader is provided in the area of the common transport roller. This measure has the advantage that the card, driven only by the common transport roller, can be moved past the read and/or write head equally far in both directions.
The restoring force can, for example, be formed by a spring acting on the articulated connection of the two pivot arms so that the transport rollers of both pivot arms are pre-stressed in their position encroaching on the card path.
In an embodiment of the invention, which is particularly simple from the design point of view, the transport rollers are mounted between the two side walls of a pivot arm, which is U-shaped in cross section. With this, it is preferred that the one U-shaped pivot arm is narrower than the other U-shaped pivot arm and encroaches between its side walls.
Furthermore, an opposing roller is provided for each transport roller, in each case on the side of the card path opposite the transport rollers, as an opposing support for the transported card.
Further advantages of the invention can be seen from the description and the drawing. Likewise, the characteristics mentioned above and those that are further specified can, according to the invention, in each case be used singly or severally in any combination. The embodiments shown and described are not to be understood as a definitive list, but rather they have more of an exemplary character to illustrate the invention.